It has long been recognized that it is possible to strengthen the muscles and tendons of a human hand by providing resistive exercises over a period of time. It has been found especially desirable to provide a device which offers adjustable resistance to the fingers, wrists and forearms being flexed in order to provide a suitable degree of exercise to the joints in motion. In the instance of post traumatic recovery, it is important to provide increasing resistance during the period when the muscles and tendons of the hand, wrist and forearms are recovering from the injury. Finger and wrist exercisers have also been suggested which would provide conditioning for a healthy hand, such a device being used by dentists, athletes or other persons requiring a high degree of manual dexterity and strength in their professions.
Moreover, a proliferation of computer keyboards in offices and homes has given rise to a dramatic increase in repetitive strain injuries such as nerve entrapments, tendon problems and muscle strain. Such injuries are commonly perceived as persistent aches or soreness in the forearms and wrists, or pain that may be felt from the shoulder to the fingertips. If left untreated, the soreness can escalate into a full blown disability.
One of the numerous types of repetitive strain injury is known as carpal tunnel syndrome. This refers to compression of the median nerve as a result of swelling of tendons and sheaths, or repeated bending of the wrist, as can occur in susceptible individuals as a result of protracted use of a computer keyboard. The position in which the hands and fingers are placed to use a keyboard typically keeps the associated muscles in flexion which may cause the carpal dome to slip in an anterior direction, causing shooting pain and numbness in the fingers. Wrist rests and other devices are commonly used to support the wrists when there is a pause during typing. However, such devices, while relieving stress on muscles and joints in some circumstances, do nothing to strengthen or rehabilitate the muscles and joints to avoid injury, or to rehabilitate from prior injury. Moreover, the advantageous aspects of wrist rests may depend on the manner in which the user's wrist is positioned. Misuse of a wrist rest may in fact cause more harm than good, increasing the potential for carpal tunnel injury.
Charles et al., U.S. Pat. No. 5,514,052 describes a “finger exerciser” which suffers from the disability of not providing a force against which to exercise the thumb because it uses an elbow anchor. The patent discloses a device for carpal tunnel syndrome having “a plurality of elastic bands” extending from a housing attached at the elbow and extending to the wrist and projecting on the inside of the wearer's palm and attached to the tips of each finger. The device is designed to exercise the extensor muscles of the hand, wrist, and fingers by having the digits extend outwardly working against the tension of the elastic bands.
Fasano, U.S. Pat. No. 3,944,220 teaches a glove which is a hand exerciser. It also fails to show a structure which is substantially stretched by the thumb, as anchoring is at the wrist. The patent describes a glove having flexible inserts radiating from the wrist to the tip of each finger embedded into the palm surface. The inserts may be tightened at the wrist to adjust the tension. However, it is difficult to see how such a device can be put on the hand without great difficulty, with fingers curled up by the elastic straps.
Harris, U.S. Pat. No. 4,455,019 discloses an exerciser for finger, hand, wrist and forearm. The exerciser consists of a frame with a hand support, a system of pulleys and weights, and finger-receiving loops. The user would insert the fingers into the loops and either extend the fingers without moving the wrist or flex the wrist backwards.
Although there are many devices in the prior art for exercising the fingers, these prior devices do a poor job of fully exercising the hand muscles. The prior art exercises for extension and flexion do not provide balanced finger extension exercise in that they are largely unable to move the thumb in its natural flexion path. More specifically, exercise devices, such as spongy balls for squeezing, coil springs and the like, and normal exercise tend to emphasize development of the muscles which close the hand into a fist. The result is that the natural position of the hand is with the fingers curled inwards. This means that the muscles are relatively short in their relaxed state and the grip of the hand is weak; loss of range of motion becomes an issue after a time. This is a natural result of aging in all people, for example exhibited as a slow closing of the hand accelerated more so at the ring and pinky fingers.
In order to strengthen the muscles and joints of the hand to avoid carpal tunnel injury or repetitive strain injuries (RSI), it is desirable to strengthen the extensor muscles and tendons to prevent those muscles from becoming overpowered by flexor muscles as well as becoming injured by repetitive strain. While various devices have been proposed which exercise the extensor muscles, such devices are inadequate due to poor design to address the causes of repetitive strain injuries
There is accordingly a need for a device which can provide these desirable capabilities to specifically address the conditioning of the thumb, fingers, wrists and forearms leading to the elbows by exercise in a natural path of motion.